The statements in this section merely provide background information related to the present disclosure and may not constitute prior art.
Hammer-drills generally include a floating rotary-reciprocatory output spindle journaled in the housing for driving a suitable tool bit coupled thereto. In operation, the spindle can be retracted axially within the housing and against the force of a suitable resilient means, upon engagement of the tool bit with a workpiece and a manual bias force exerted by the operator on the tool. A non-rotating hammer member can be secured in the housing, and a rotating hammer member can be carried by the spindle. The hammer members can have ratcheting engagement together to impart a series of vibratory impacts to the spindle in a “hammer-drilling” mode of operation. A shiftable member can act upon the spindle to change from a “drilling” mode to the “hammer-drilling” mode, and vice versa. In the drilling mode, the cooperating hammer members are spaced too far apart and hence do not engage each other. In the hammer-drilling mode, the spacing between the ratcheting teeth is reduced, allowing the cooperating hammer members impart vibratory impacts to the spindle.